1. Field of the Invention
The present invention provides a drum type washing machine comprising an outer cabinet, a water tub provided in the outer cabinet, a rotating tub provided for rotation in the water tub, the rotating tub having a front and a rear, an electric motor driving the rotating tub, an elastic supporting element elastically supporting the water tub, and a loading element loading the supporting element and having a center of gravity located between substantially the middle of a dimension from the front to the rear of the rotating tub and the rear of the rotating tub, wherein the elastic supporting element includes a pair of front supporting members disposed ahead of the center of gravity of the loading element and a pair of rear supporting members disposed in the rear of the center of gravity of the loading element, and a distance from each front supporting member to the center of gravity of the loading element is substantially equal to a distance from each rear supporting member to the center of gravity of the loading element.
2. Description of the Related Art
An electric motor 109 is provided on a lower portion of the water tub 102. The motor 109 includes a rotational shaft 109a on which a driving pulley 110 is mounted. A transmission belt 112 extends between the pulleys 110 and 108. The pulleys 108 and 110 and the belt 112 constitute a belt transmission mechanism 111. In the above-described construction, torque developed by the motor 109 is transmitted via the belt transmission mechanism 111 to the rotating tub 104 so that the tub is rotated.
In the drum type washing machines such as described above, vibration or oscillation generally tends to be produced during a dehydrating or spinning operation since laundry stuck to the inner circumferential face of the rotating tub 104 is raised against gravity. For reduction in the vibration, counterbalances 113 and 114 are mounted on upper and lower front portions respectively so that load is uniformly applied to the suspension mechanisms 103 and so that weight distribution with respect to the center of rotation of the rotating tub 104 is well balanced.
However, an amount of load received by each suspension mechanism 103 is varied due to an amount of the laundry accommodated in the rotating tub or the weight distribution with respect to the center of rotation during the washing or dehydrating operation. As a result, a sufficient amount of vibration due to rotation of the rotating tub 104 cannot be reduced. Thus, a further improvement is desired.
Therefore, an object of the present invention is to provide a drum type washing machine in which the vibration due to rotation of the rotating tub can effectively be reduced.
The present invention provides a drum type washing machine comprising an outer cabinet, a water tub provided in the outer cabinet, a rotating tub provided for rotation in the water tub, the rotating tub having a front and a rear, an electric motor driving the rotating tub, an elastic supporting element elastically supporting the water tub, and a loading element loading the supporting element and having a center of gravity located between substantially the middle of a dimension from the front to the rear of the rotating tub and the rear of the rotating tub, wherein the elastic supporting element includes a pair of front supporting members disposed ahead of the center of gravity of the loading element and a pair of rear supporting members disposed in the rear of the center of gravity of the loading element, and a distance from each front supporting member to the center of gravity of the loading element is substantially equal to a distance from each rear supporting member to the center of gravity of the loading element.
There are several causes for the vibration due to rotation of the rotating tub. The inventors noted one of such causes, that is, a location of the center of gravity of a member (a loading element) loading the elastic supporting element. The inventors carried out an experiment to confirm the relationship between the location of the center of gravity of the loading element and occurrence of vibration. The experiment shows that the vibration is reduced when the center of gravity of the loading element is located between substantially the middle of a back-and-forth dimension from the front to the rear of the rotating tub and the rear of the rotating tub. The above-described construction can reduce the vibration and noise produced during rotation of the rotating tub. Further, the water tub can stably be supported on the two pairs of the supporting members disposed ahead of and in the rear of the center of gravity of the loading element. Moreover, since the load of the loading element is applied uniformly to the supporting members, the vibration due to rotation of the rotating tub can be reduced.
The drum type washing machine preferably further comprises a bearing assembly provided on the rear of the water tub for supporting the rotating tub for rotation. In this case, the loading element includes at least the water tub, rotating tub, bearing assembly and motor. Each of the water tub, rotating tub, bearing assembly and motor contributes to the center of gravity of the loading element since each of them has a relatively large weight. Accordingly, when the weights of these parts and locational relations among these parts are adjusted during the manufacture, the center of gravity of the loading element can be set at a suitable location.
Either the water tub or the rotating tub is preferably provided with a counterweight disposed ahead of substantially the middle of the dimension from the front to the rear of the rotating tub. A location and weight of the counterweight are adjusted such that the center of gravity of the loading element can easily be set at a suitable location.
The elastic supporting element preferably includes a pair of front supporting members disposed ahead of the center of gravity of the loading element and a pair of rear supporting members disposed in the rear of the center of gravity of the loading element, and a distance from each front supporting member to the center of gravity of the loading element is substantially equal to a distance from each rear supporting member to the center of gravity of the loading element. Consequently, the water tub can stably be supported on the two pairs of the supporting members disposed ahead of and in the rear of the center of gravity of the loading element. Moreover, since the load of the loading element is applied uniformly to the supporting members, the vibration due to rotation of the rotating tub can be reduced.
The elastic supporting element preferably includes a pair of front supporting members disposed ahead of the center of gravity of the loading element and a pair of rear supporting members disposed in the rear of the center of gravity of the loading element, and a distance from each front supporting member to the center of gravity of the loading element is substantially longer than a distance from each rear supporting member to the center of gravity of the loading element. Since a distance or span between the two pairs of the supporting members supporting the water tub is increased, the water tub can further stably be supported.
The load of the loading element is applied non-uniformly to the front and rear supporting members when the distance from the center of gravity of the loading element to each front supporting member differs from the distance from the center of gravity of the loading element to each rear supporting member. To solve the problem, the drum type washing machine preferably further comprises a first fixing member to which the front supporting member is fixed and a second fixing member to which the rear supporting member is fixed. In this construction, a mounting dimension from the first fixing member to a portion of each front supporting member on which the water tub is supported differs from a mounting dimension from the second fixing member to a portion of each rear supporting member on which the water tub is supported. Even when the load applied to each front supporting member differs from the load applied to each rear supporting member, the mounting dimension of each front supporting member differs from that of each rear supporting member such that the inclination of the loading element or the water tub can be adjusted.
Each front supporting member preferably includes a first spring to which the load of the loading element is applied, each rear supporting member includes a second spring to which the load of the loading element is applied, and each first spring has a free length differing from a free length of each second spring. In this construction, the free length of each first spring is set at a suitable value differing from that of the free length of each second spring such that the inclination of the water tub can be adjusted.
Each front supporting member preferably includes a first spring to which the load of the loading element is applied, each rear supporting member includes a second spring to which the load of the loading element is applied, and each first spring has a spring constant differing from a spring constant of each second spring. Consequently, the spring constants of the first and second springs are set at suitable values respectively so that the inclination of the water tub can be adjusted.
The invention also provides a drum type washing machine comprising an outer cabinet, a water tub provided in the outer cabinet, a drum type rotating tub provided for rotation in the water tub, the rotating tub having a front and a rear, an electric motor driving the rotating tub, an elastic supporting element elastically supporting the water tub, and a loading element loading the supporting element and having a center of gravity located between substantially the middle of a dimension from the front to the rear of the rotating tub and the rear of the rotating tub. In this construction, the elastic supporting element includes a pair of the elastic supporting elements including respective portions on which the water tub is supported, the portions being located ahead of the center of gravity of the loading element between the center of gravity of the loading element and another center of gravity of the loading element in a case where an allowable maximum amount of laundry is accommodated in the rotating tub.
The drum type washing machine generally performs a drying operation as well as the washing and dehydrating operations. A maximum amount of laundry to be dried in one drying operation is about one half of a maximum amount of laundry to be washed and dehydrated, that is, a maximum amount of laundry allowed to be accommodated in the rotating tub. Amounts of vibration and noise produced during the dehydrating operation are larger than during the washing and drying operations since the rotating tub is rotated at high speeds in the dehydrating operation. The inventors then regarded substantially one half of the maximum amount of laundry allowed to be accommodated in the rotating tub as a standard amount of laundry. Consequently, since the water tub can stably be supported by the elastic supporting element when the standard amount of laundry is dehydrated, the vibration and noise can effectively be reduced.
The drum type washing machine preferably further comprises a limiting element which limits a back-and-forth movement of the water tub. Consequently, the back-and-forth movement of the water tub which tends to result from the support of the water tub by the paired elastic supporting members can be limited.
The drum type washing machine preferably further comprises a balancer provided on the front of the rotating tub. This construction can prevent the rotating tub from being rotated with a swinging motion, thereby reducing the vibration and noise.
The rotating tub preferably has a rotation axis inclined rearwardly downward relative to a horizontal axis. In this construction, the laundry accommodated in the rotating tub are located deep in the tub such that the laundry is not displaced so much. Accordingly, the center of gravity of the loading element is not shifted so much and the balance of weight is difficult to lose. Consequently, the water tub can stably be supported by the elastic supporting element.